Factors Affecting the Growth and Hyoscyamine Production during Batch Culture of Transformed Roots of Datura stramonium

Abstract

The growth and hyoscyamine production of transformed roots of Datura stramonium (cell line DS 1) were investigated in batch culture experiments at three different temperatures and in media of varying total ion composition and sucrose level. Growth rate was not greatly affected by the level of Gamborg's B5 salts or the sucrose concentration. Growth rates of roots in a range of media were similar at 25°C (doubling time T_d 1.2-1.6 days) and at 30°C (T_d 1.2-1.7 days) but roots grew slower at 20°C (T_d 1.9-3.5 days). The total root yield on a fresh weight basis was higher in full strength B5 media compared with half strength B5 media at all sucrose levels tested. However, the dry weight content of the roots increased significantly (4-20%) as the sucrose level in the medium was raised (2-10%) at each of the three temperatures. At 20°C, the hyoscyamine content of the roots was higher than that at 25°C or 30°C at all sucrose levels tested and was unaffected by increasing sucrose levels. However, increasing the level of sucrose (1-5%) in either half or full strength B5 media at 25°C or 30°C increased the hyoscyamine content of the roots by up to eight fold. At 20°C, the total yield of hyoscyamine per flask or per unit of sucrose supplied was also higher than at 25°C or 30°C with sucrose levels up to 5%. The highest rates of hyoscyamine production by cell line DS 1 were obtained with full strength B5 medium with 5% sucrose at either 20°C or 25°C. Under these conditions, rates of hyoscyamine formation of up to 7.4 mg/l/d were observed under batch culture conditions. The amount of hyoscyamine released into the culture medium was much greater at 30°C (up to 14% of the total) than at either 20°C or 25°C (up to 4% of the total).

Key words

Datura stramonium - batch culture - growth - hyoscyamine - transformed roots